A watch movement provided with two springs and with two barrels has been described in document CH 610 465. Two embodiments are envisaged. In the first, the barrels are coaxial while in the second they are placed side-by-side.
A coaxial arrangement of two barrels makes it possible to produce a movement whose area remains small, but which has a relatively large thickness. In contrast, the thickness may be small when the barrels are placed side by side, but they occupy a large area of the movement, corresponding to a sector of about 180°.
To produce watches with a power reserve as large as possible, document EP 1 115 040 proposes to provide a watch with four barrels, placed coaxially in pairs. Such a solution makes it possible not only to store a large amount of potential energy, thereby guaranteeing operation for more than one week, but also to restore it with a speed and a torque that are compatible with a customary going train.
In this construction, the two pairs of coaxial barrels occupy practically the entire thickness of the movement and a sector of around 180°. Under such conditions, the power reserve is admittedly Large, but it is difficult to house mechanisms providing complementary functions. Thus, a power reserve indicator mechanism is placed between the barrels, within their thickness, which means that the coaxial pairs are far apart and must be linked to each other by a gear train. The area of the movement thus occupied is thereby further increased.
Document WO 03/001304 describes a watch movement comprising several barrels, two at a first level and five others placed at a second level lying between the first level and the display means. Admittedly, such a solution provides a particularly large power reserve, but makes it practically impossible to display additional functions.